Demos/Host/LowLevel/KeyboardHostWithParser/ConfigDescriptor.c

   1 /*
   2              LUFA Library
   3      Copyright (C) Dean Camera, 2013.
   4
   5   dean [at] fourwalledcubicle [dot] com
   6            www.lufa-lib.org
   7 */
   8
   9 /*
  10   Copyright 2013  Dean Camera (dean [at] fourwalledcubicle [dot] com)
  11
  12   Permission to use, copy, modify, distribute, and sell this
  13   software and its documentation for any purpose is hereby granted
  14   without fee, provided that the above copyright notice appear in
  15   all copies and that both that the copyright notice and this
  16   permission notice and warranty disclaimer appear in supporting
  17   documentation, and that the name of the author not be used in
  18   advertising or publicity pertaining to distribution of the
  19   software without specific, written prior permission.
  20
  21   The author disclaims all warranties with regard to this
  22   software, including all implied warranties of merchantability
  23   and fitness.  In no event shall the author be liable for any
  24   special, indirect or consequential damages or any damages
  25   whatsoever resulting from loss of use, data or profits, whether
  26   in an action of contract, negligence or other tortious action,
  27   arising out of or in connection with the use or performance of
  28   this software.
  29 */
  30
  31 /** \file
  32  *
  33  *  USB Device Configuration Descriptor processing routines, to determine the correct pipe configurations
  34  *  needed to communication with an attached USB device. Descriptors are special  computer-readable structures
  35  *  which the host requests upon device enumeration, to determine the device's capabilities and functions.
  36  */
  37
  38 #include "ConfigDescriptor.h"
  39
  40 /** Reads and processes an attached device's descriptors, to determine compatibility and pipe configurations. This
  41  *  routine will read in the entire configuration descriptor, and configure the hosts pipes to correctly communicate
  42  *  with compatible devices.
  43  *
  44  *  This routine searches for a HID interface descriptor containing at least one Interrupt type IN endpoint and HID descriptor.
  45  *
  46  *  \return An error code from the \ref KeyboardHostWithParser_GetConfigDescriptorDataCodes_t enum.
  47  */
  48 uint8_t ProcessConfigurationDescriptor(void)
  49 {
  50         uint8_t  ConfigDescriptorData[512];
  51         void*    CurrConfigLocation = ConfigDescriptorData;
  52         uint16_t CurrConfigBytesRem;
  53
  54         USB_Descriptor_Interface_t* HIDInterface   = NULL;
  55         USB_HID_Descriptor_HID_t*   HIDDescriptor  = NULL;
  56         USB_Descriptor_Endpoint_t*  DataINEndpoint = NULL;
  57
  58         /* Retrieve the entire configuration descriptor into the allocated buffer */
  59         switch (USB_Host_GetDeviceConfigDescriptor(1, &CurrConfigBytesRem, ConfigDescriptorData, sizeof(ConfigDescriptorData)))
  60         {
  61                 case HOST_GETCONFIG_Successful:
  62                         break;
  63                 case HOST_GETCONFIG_InvalidData:
  64                         return InvalidConfigDataReturned;
  65                 case HOST_GETCONFIG_BuffOverflow:
  66                         return DescriptorTooLarge;
  67                 default:
  68                         return ControlError;
  69         }
  70
  71         while (!(DataINEndpoint))
  72         {
  73                 /* See if we've found a likely compatible interface, and if there is an endpoint within that interface */
  74                 if (!(HIDInterface) ||
  75                     USB_GetNextDescriptorComp(&CurrConfigBytesRem, &CurrConfigLocation,
  76                                               DComp_NextKeyboardInterfaceDataEndpoint) != DESCRIPTOR_SEARCH_COMP_Found)
  77                 {
  78                         /* Get the next HID interface from the configuration descriptor */
  79                         if (USB_GetNextDescriptorComp(&CurrConfigBytesRem, &CurrConfigLocation,
  80                                                                                   DComp_NextKeyboardInterface) != DESCRIPTOR_SEARCH_COMP_Found)
  81                         {
  82                                 /* Descriptor not found, error out */
  83                                 return NoCompatibleInterfaceFound;
  84                         }
  85
  86                         /* Save the interface in case we need to refer back to it later */
  87                         HIDInterface = DESCRIPTOR_PCAST(CurrConfigLocation, USB_Descriptor_Interface_t);
  88
  89                         /* Get the HID descriptor from the configuration descriptor */
  90                         if (USB_GetNextDescriptorComp(&CurrConfigBytesRem, &CurrConfigLocation,
  91                                                                                   DComp_NextHID) != DESCRIPTOR_SEARCH_COMP_Found)
  92                         {
  93                                 /* Descriptor not found, error out */
  94                                 return NoCompatibleInterfaceFound;
  95                         }
  96
  97                         /* Save the HID descriptor for later use */
  98                         HIDDescriptor = DESCRIPTOR_PCAST(CurrConfigLocation, USB_HID_Descriptor_HID_t);
  99
 100                         /* Skip the remainder of the loop as we have not found an endpoint yet */
 101                         continue;
 102                 }
 103
 104                 /* Retrieve the endpoint address from the endpoint descriptor */
 105                 USB_Descriptor_Endpoint_t* EndpointData = DESCRIPTOR_PCAST(CurrConfigLocation, USB_Descriptor_Endpoint_t);
 106
 107                 /* If the endpoint is a IN type endpoint */
 108                 if ((EndpointData->EndpointAddress & ENDPOINT_DIR_MASK) == ENDPOINT_DIR_IN)
 109                   DataINEndpoint = EndpointData;
 110         }
 111
 112         /* Configure the HID data IN pipe */
 113         Pipe_ConfigurePipe(KEYBOARD_DATA_IN_PIPE, EP_TYPE_INTERRUPT, DataINEndpoint->EndpointAddress, DataINEndpoint->EndpointSize, 1);
 114         Pipe_SetInterruptPeriod(DataINEndpoint->PollingIntervalMS);
 115
 116         /* Get the HID report size from the HID report descriptor */
 117         HIDReportSize = HIDDescriptor->HIDReportLength;
 118
 119         /* Valid data found, return success */
 120         return SuccessfulConfigRead;
 121 }
 122
 123 /** Descriptor comparator function. This comparator function is can be called while processing an attached USB device's
 124  *  configuration descriptor, to search for a specific sub descriptor. It can also be used to abort the configuration
 125  *  descriptor processing if an incompatible descriptor configuration is found.
 126  *
 127  *  This comparator searches for the next Interface descriptor of the correct Keyboard HID Class and Protocol values.
 128  *
 129  *  \return A value from the DSEARCH_Return_ErrorCodes_t enum
 130  */
 131 uint8_t DComp_NextKeyboardInterface(void* CurrentDescriptor)
 132 {
 133         USB_Descriptor_Header_t* Header = DESCRIPTOR_PCAST(CurrentDescriptor, USB_Descriptor_Header_t);
 134
 135         if (Header->Type == DTYPE_Interface)
 136         {
 137                 USB_Descriptor_Interface_t* Interface = DESCRIPTOR_PCAST(CurrentDescriptor, USB_Descriptor_Interface_t);
 138
 139                 /* Check the HID descriptor class, break out if correct class interface found */
 140                 if (Interface->Class == HID_CSCP_HIDClass)
 141                 {
 142                         return DESCRIPTOR_SEARCH_Found;
 143                 }
 144         }
 145
 146         return DESCRIPTOR_SEARCH_NotFound;
 147 }
 148
 149 /** Descriptor comparator function. This comparator function is can be called while processing an attached USB device's
 150  *  configuration descriptor, to search for a specific sub descriptor. It can also be used to abort the configuration
 151  *  descriptor processing if an incompatible descriptor configuration is found.
 152  *
 153  *  This comparator searches for the next Endpoint descriptor inside the current interface descriptor, aborting the
 154  *  search if another interface descriptor is found before the required endpoint.
 155  *
 156  *  \return A value from the DSEARCH_Return_ErrorCodes_t enum
 157  */
 158 uint8_t DComp_NextKeyboardInterfaceDataEndpoint(void* CurrentDescriptor)
 159 {
 160         USB_Descriptor_Header_t* Header = DESCRIPTOR_PCAST(CurrentDescriptor, USB_Descriptor_Header_t);
 161
 162         if (Header->Type == DTYPE_Endpoint)
 163           return DESCRIPTOR_SEARCH_Found;
 164         else if (Header->Type == DTYPE_Interface)
 165           return DESCRIPTOR_SEARCH_Fail;
 166         else
 167           return DESCRIPTOR_SEARCH_NotFound;
 168 }
 169
 170 /** Descriptor comparator function. This comparator function is can be called while processing an attached USB device's
 171  *  configuration descriptor, to search for a specific sub descriptor. It can also be used to abort the configuration
 172  *  descriptor processing if an incompatible descriptor configuration is found.
 173  *
 174  *  This comparator searches for the next HID descriptor within the current HID interface descriptor.
 175  *
 176  *  \return A value from the DSEARCH_Return_ErrorCodes_t enum
 177  */
 178 uint8_t DComp_NextHID(void* CurrentDescriptor)
 179 {
 180         USB_Descriptor_Header_t* Header = DESCRIPTOR_PCAST(CurrentDescriptor, USB_Descriptor_Header_t);
 181
 182         if (Header->Type == HID_DTYPE_HID)
 183           return DESCRIPTOR_SEARCH_Found;
 184         else if (Header->Type == DTYPE_Interface)
 185           return DESCRIPTOR_SEARCH_Fail;
 186         else
 187           return DESCRIPTOR_SEARCH_NotFound;
 188 }
 189